About
APRS, Automatic Packet Reporting System is an ham radio-system that uses packet radio to send real time tactical information.
APRS has been developed by Bob Bruninga, callsign WB4APR.
More information about APRS can be found at www.aprs.org or at wikipedia.
The goal of this website is to present all sent aprs information (that has reached an igate) in a user friendly way. This website is maintained by me Per Qvarforth SM4WJF (I'm a Swedish ham radio operator).
I named the website APRS Direct since each user browser will be connected directly to our own APRS-IS server (with no intermediate database-server). By having a direct connection to an APRS-IS server we can achive a REAL real-time APRS feed.
Contact us
Please feel free to contact me by email: per@aprsdirect.com.
If you have feedback regarding the website functionality or if you have found an error I will do my best to fix it.
Technical description
- All APRS data is collected from the APRS-IS network.
- The real time feed is achived by letting the browser connect to our own APRS-IS server through a websocket connection.
- The heatmap that is shown when you zoom out is generated once every hour.
- The raw feed shown at the bottom of the website includes all packets that has been added to the map. If you move around on the map more packets will be added to the map.
- Note that the time-interval specified in the station info-window (on the map) is how long a station has been on that location without any downtime longer than 24h.
- The initial map position is based on your IP address. This is achived by using the GeoLite2 data created by MaxMind, available from http://www.maxmind.com.
- The geographical data like city locations is received from http://www.geonames.org/.
Marker logic
More about our brilliant marker logic :-)
- It is possible to have several stations with the same name as long as the sender and symbol is different (we only allow a sender to take over another sender's object if it looks like they are referring to the same real world object).
- It's even possible to have several markers with the same name, same SSID and the same sender as long as they are considered stationary. I do not recommend relying on this feature since APRS is not designed this way (and few other clients will handle it).
- We have an adaptive speed limit filter and other filters that sorts out packets that has a faulty position.
- If a moving station sends a packet that is sorted out by our adaptive speed limit filter the packet will be marked as unconfirmed, if we later receive a packet that confirmes that the station is moving in that direction the previous packet will be confirmed.
- If a station moves in one area and suddently appear in another area the two tails will be connected by a dashed polyline.
- Packets that has been sorted out by our filters are considered to be ghost-markers, they can be shown by clicking "Show ghosts markers" in the menu.
- A moving station that reports it's speed and direction will have an animated direction polyline (will be hidden after 15min).
- The dotted polyline shows the packet transmit path, will be shown when you hover over a marker or a "dotmarker". If a station in the path hasn't sent a position packet in a long time it will show up for some seconds and than disappear again.
- Want more information? Mail me!
Short about the code
- The collector and websocket server is written in Python.
- The website client is mainly written in javascript.
- The aprs symbol generator and our own website framework is written in PHP.
Credits
- Thanks to Bob Bruninga, WB4APR for developing APRS.
- Thanks to Rossen Georgiev for the APRS library for Python, used for interacting with our APRS-IS server.
- Thanks to Matti Aarnio, OH2MQK and Heikki Hannikainen, OH7LZB for aprsc (an APRS-IS server for Linux)
- Thanks to Jeffrey J. Guy for heatmap (a Python module used to create heatmaps).
- Thanks to all APRS-users that has tested my website!
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